This invention relates to fire fighting equipment, and more particularly to a safety mechanism for a portable monitor.
An effective piece of fire fighting equipment is known in this art as a monitor, which is essentially a water gun that produces a powerful stream of water. The stream leaving the nozzle produces such a strong reaction force that the nozzle cannot be controlled by hand. Instead, the nozzle either is mounted on a deck mount base which is secured to, for example, the top of a truck, or is mounted on a portable ground base which rests on a support surface such as the ground. In both instances, the nozzle may be manually turned on a vertical axis to change the direction of the stream and turned on a horizontal axis to change the angle of elevation of the stream.
A typical portable ground base includes a conduit between a supply hose and the monitor and legs or braces which radiate outwardly from the underside of the conduit and support the conduit on the ground. This gives rise to a safety problem because it is not firmly secured to the ground. When the angle of elevation of the discharge nozzle is too low (too close to the horizontal), the strong reaction force of the stream may cause the monitor and the base to lift up and tip to one side and flip wildly about. This situation is dangerous because the stream is powerful enough to injure a person, and it is difficult to get the monitor under control once it tips over.
Some monitors have included a safety pin which prevents the angle of elevation from being lowered below a certain angle (such as 35.degree.) to a danger zone, but a safety pin can usually be removed or overridden. A monitor should always be tied to a stationary object, but sometimes under emergency conditions this is not always accomplished. Even if a safety pin is used and/or the monitor is tied another object, it could still tip and get out of control.
It is a general object of this invention to avoid the foregoing problems by providing a safety mechanism for automatically reducing the flow of water to the monitor in the event the monitor and the ground base start to lift off the ground.